use error scope to handle errors on shader module creation

Author: jakobhellermann

crates/bevy_render/Cargo.toml

@@ -66,3 +66,4 @@ flate2 = { version = "1.0.22", optional = true }
 ruzstd = { version = "0.2.4", optional = true }
 # For transcoding of UASTC/ETC1S universal formats, and for .basis file support
 basis-universal = { version = "0.2.0", optional = true }
+futures-util = "0.3"

crates/bevy_render/src/render_resource/pipeline_cache.rs

@@ -85,9 +85,20 @@ impl ShaderCache {
                         return Err(RenderPipelineError::AsModuleDescriptorError(err, processed));
                     }
                 };
-                entry.insert(Arc::new(
-                    render_device.create_shader_module(&module_descriptor),
-                ))
+
+                render_device
+                    .wgpu_device()
+                    .push_error_scope(wgpu::ErrorFilter::Validation);
+                let shader_module = render_device.create_shader_module(&module_descriptor);
+                use futures_util::future::FutureExt;
+                let error = render_device.wgpu_device().pop_error_scope();
+                if let Some(Some(wgpu::Error::Validation { description, .. })) =
+                    error.now_or_never()
+                {
+                    return Err(RenderPipelineError::CreateShaderModule(description));
+                }
+
+                entry.insert(Arc::new(shader_module))
             }
         };
 
@@ -226,6 +237,8 @@ pub enum RenderPipelineError {
     AsModuleDescriptorError(AsModuleDescriptorError, ProcessedShader),
     #[error("Shader import not yet available.")]
     ShaderImportNotYetAvailable,
+    #[error("{0}")]
+    CreateShaderModule(String),
 }
 
 impl RenderPipelineCache {
@@ -304,6 +317,10 @@ impl RenderPipelineCache {
                             log_shader_error(source, err);
                             continue;
                         }
+                        RenderPipelineError::CreateShaderModule(description) => {
+                            error!("failed to create shader module: {}", description);
+                            continue;
+                        }
                     }
                 }
             }

crates/bevy_render/src/render_resource/shader.rs

@@ -161,9 +161,9 @@ impl ProcessedShader {
             source: match self {
                 ProcessedShader::Wgsl(source) => {
                     #[cfg(debug_assertions)]
-                    // This isn't neccessary, but catches errors early during hot reloading of invalid wgsl shaders.
-                    // Eventually, wgpu will have features that will make this unneccessary like compilation info
-                    // or error scopes, but until then parsing the shader twice during development the easiest solution.
+                    // Parse and validate the shader early, so that (e.g. while hot reloading) we can
+                    // display nicely formatted error messages instead of relying on just displaying the error string
+                    // returned by wgpu upon creating the shader module.
                     let _ = self.reflect()?;
 
                     ShaderSource::Wgsl(source.clone())